<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            padding: 0;
            margin: 0;
            /* 2022-3-30 */
            /* lixiaolong */
        }

        ul,
        li {
            list-style: none;
        }

        ul {
            width: 300px;
            height: 200px;
            background: #eee;
            margin: 100px auto;
            display: flex;

            flex-wrap: wrap;
            align-items: center;
        }

        li {
            width: 90px;
            border-right: 1px solid #ccc;
            margin-top: 10px;
            margin-bottom: 10px;
            text-align: center;
        }

        li:nth-child(3),
        li:nth-child(6),
        li:last-child {
            border-right: none;
        }
    </style>
</head>

<body>
    <ul>
        <li>边界线</li>
        <li>边界线</li>
        <li>边界线</li>
        <li>边界线</li>
        <li>边界线</li>
        <li>边界线</li>
        <li>边界线</li>
    </ul>
</body>

</html>